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Current Issue » November 2013

From the River Valley Fliers RC Club, Plover-Wausau, Wisconsin

Paint Compatibility

by Wayne Dempze

Finishing materials, and especially some of the solvents they contain, react with one another. A lacquer applied over an old coat of the same material will partially dissolve the dry paint, so lacquers rarely peel. Sometimes, when one kind of paint is put over another, the whole finish may dissolve and wrinkle up. We call this a compatibility problem.


The table below shows what material can be applied over others. We think you’ll find it easy to use. For example, a builder might wish to use Aero Gloss dope over a butyrate dope. Find Aero Gloss dope in the top row which is labeled Over. Find the butyrate dope in the left column labeled Under. The “N” in the table shows the combination not to be compatible.


Maybe a model was originally sealed with dope over the alkyd as the table shows. Perhaps a builder wished to paint a model with one kind of paint and trim it with another. The compatibility table shows if the trim will react with the base color; however, I don’t recommend this practice.


Here’s another example on how to use the chart. Vinyl spackle is compatible over polyester resin. Find vinyl spackle in the Over section and read down to polyester resin. Now let’s reverse the two materials. Vinyl spackle is not compatible when put Under polyester resin.


Incidentally, always sand any color paint with 320 or 400 grit between coats. Sometimes paints need the rough texture to bite into; not all finishes partially dissolve earlier coats like lacquers do.


No doubt, some very skilled wood finishers may have been able to use materials in a way we say is incompatible. The table favors a conservative, safe approach. Compatibility characteristics change considerably with brands, weather, method of application, and the reducers used. A finisher using materials other than those listed had better plan to test for compatibility on a scrap of wood prepared in the same fashion as the model.

 

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November 2013
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President to President
Information Resources

On the Safe Side
Flightline Comnunication

Leader to Leader
National Model Aviation Day was a Success

Editor's Picks
Renewal Time

Know Your Site Owner's Policies

Six Keys to Success for New Pilots

Fuel: The Ins and Outs

Setting Up Your Servos

Eliminate Bounce in Your Landings

AMA Insider Archives Will Remain

Tips & Tricks

 

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